The MTFCA Carburetor Book does not seem to mention the size for a Holley NH Needle Valve Thread Tap.
Measurement wise the threads appear to be a 14-32, but might be a 1/4-32.
Does anyone know for sure the Needle Valve Thread size or where to get a tap?
Here's a 2010 thread that talks about NH thread sizes:
That is everything I needed to know and I did not know who to ask.